Spokane region Interstate 90 - Severe congestion
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Measures of severe congestion on the I-90 corridor in the Spokane region
Severe congestion
Severe congestion occurs when highway travel speeds are slower than 60% of the posted speed (about 36 mph for a 60 mph speed limit). During this situation, vehicle speeds and spacing decrease along with reduced highway efficiency well below maximum productivity. See WSDOT's how to calculate severe congestion (PDF 5.9MB).
Sources: WSDOT Transportation Safety and Systems Analysis Division and WSDOT TRACFLOW (https://tracflow.wsdot.wa.gov/)
Annual highlights
In 2022, severe congestion increased compared to 2021, due to the ongoing recovery of traffic volume in the wake of COVID-19. Severe congestion in 2022 is even more than the pre-pandemic level. Commuters driving westbound between Argonne Road and Division Street on I-90 experienced more severe congestion (speeds of 36 mph or less) than 2021 during morning rush hours. For example, at 7:45 p.m. speeds on this commute were below 36 mph on 16.6% of weekdays in 2022 —up from 12.6% in 2021.
In 2022, the evening eastbound commute between Division Street and Argonne Road experienced more severe congestion compared to 2021. For example, at 5:20 p.m. 42.0% of weekday commuters in 2022 experienced congestion compared to 23.4% in 2021.
In 2021, severe congestion increased compared to 2020, due to the ongoing recovery of traffic volume in the wake of COVID-19, but it was still lower than the pre-pandemic level. Commuters driving westbound between Argonne Road and Division Street on I-90 experienced more severe congestion (speeds of 36 mph or less) than 2020 during morning rush hours. For example, at 7:45 p.m. speeds on this commute were below 36 mph on 12.6% of weekdays in 2021—up from 0.4% in 2020.
In 2021, the evening eastbound commute between Division Street and Argonne Road experienced more severe congestion compared to 2020. For example, at 5:20 p.m. 23.4% of weekdays commuters in 2021 experienced congestion compared to 18.0% in the 2020.
In 2020, due to the statewide response to COVID-19 there was significant decrease in severe congestion compared to previous years. Commuters driving westbound between Argonne Road and Division Street on I-90 did so in severely congested conditions (speeds of 36 mph or less) significantly less in 2020 than in 2019 during morning rush hours. For example, at 7:45 a.m. speeds on this commute were below not 36 mph on 0.4% of weekdays in 2020—down from 25.3% of weekdays in 2019.
In 2020, the evening commute between eastbound Division Street and Argonne Road experienced less congestion compared to 2019. For example, at 5:15 p.m. 19.9% of weekdays in 2019 saw severe congestion compared to 48.5% in the 2019.
Commuters driving westbound between Argonne Road to Division Street on I-90 drove in severely congested conditions (speeds of 36 mph or less) less often in 2019 than in 2018 during morning rush hours. For example, at 7:45 a.m. speeds on this commute were below 36 mph on 25.3% of weekdays in 2019—down from 24.1% of weekdays in 2018.
In 2019, the evening commute between eastbound Division Street to Argonne Road experienced more congestion compared to 2018. For example, at 5:20 p.m. 53.1% of weekdays in 2019 saw severe congestion compared to 23.0% in the 2018.
Commuters driving westbound between Argonne Road to Division Street on I-90 drove in severely congested conditions (speeds of 36 mph or less) less often in 2018 than in 2017 during evening rush hours. For example, at 5:20 p.m. speeds on this commute were below 36 mph on 10.7% of weekdays in 2018—down from 16.5% of weekdays in 2017.
In 2018, the evening commute between eastbound Division Street to Argonne Road experienced more congestion compared to 2017. For example, at 5:15 p.m. 19.2% of weekdays in 2018 saw severe congestion compared to 9.6% in the 2017.